Vitamin D, 25-OH
Measures 25-hydroxyvitamin D, the main form stored in your body from sun, food, and supplements. Used when bone risk, low or high D, or absorption issues are in question.
Vitamin D is less a vitamin and more a hormone your skin makes from sun, with backup from food and pills. The 25-hydroxyvitamin D blood test measures what is stored in your body, not the quick spike from today's supplement. Bones, calcium balance, muscles, and immune chatter all lean on this level. Your doctor uses the result to decide whether sun, diet, or a careful supplement plan is worth it, and to avoid quietly running too high.
Self-Pay Price Comparison
| Provider | Price | vs. Highest | Order |
|---|---|---|---|
Quest QuestHealth self-pay | $75.00 | Save $24.00 | Order · Quest |
LabCorp Labcorp OnDemand | $99.00 | Highest | Order · LabCorp |
GoodLabs Discount lab network | $11.00Best value | Best price | Order · GoodLabs |
What This Test Measures
This test measures total 25-hydroxyvitamin D, the form your body warehouses before turning it into the active hormone. Here is what that storage number means:
The storage pool of vitamin D built from sun, food, and pills before the body activates it; low values point to shortfall from lack of sun, poor intake, malabsorption, or interfering medicines, high values usually mean supplementation overshot and can drive calcium too high.
How to Read Your Results
Labs print your 25-OH D next to overlapping expert bands and sometimes split D2 versus D3. Here is how to read the three result stories without chasing noise:
| Marker | Normal Range | If Flagged | What It Might Mean |
|---|---|---|---|
| 25-hydroxyvitamin D (interpretation bands) | MedlinePlus Medical Encyclopedia (25-hydroxy vitamin D test): many experts cite roughly 20-40 ng/mL (about 60-100 nmol/L); others cite roughly 30-50 ng/mL (about 75-125 nmol/L). Laboratories may report either unit. | abnormal | Sitting below those bands often fits deficiency from sun, diet, malabsorption, or medicines such as phenytoin. One result in isolation rarely tells the full story; your doctor may confirm before megadosing. |
| 25-hydroxyvitamin D (low) | Same sources as above; individual targets vary with bone risk and other labs. | low | Low storage D is common in older adults, breastfed infants without supplementation, obesity, and chronic kidney or liver disease. Symptoms can be silent until bones complain. |
| 25-hydroxyvitamin D (high) | MedlinePlus Medical Encyclopedia notes hypervitaminosis D is most often from taking too much vitamin D. | high | Usually reflects over-supplementation and can drive high blood calcium and kidney stress. Stop guessing; let your doctor unwind doses using repeat labs. |
When to Order
Annual baseline
Not everyone needs yearly screening; MedlinePlus notes universal adult screening is generally not recommended, but many people still check when risk adds up.
Osteoporosis, stress fractures, or long-term steroid use
Bone risk workups often include 25-OH vitamin D because calcium absorption leans on it.
Limited sun, darker skin, or always using high-SPF coverage
Skin makes less vitamin D in those settings; a level shows whether food or supplements need to step in.
Malabsorption (celiac, Crohn, ulcerative colitis, bariatric surgery)
Gut and surgery history steal absorption; testing guides replacement safely.
Taking high-dose vitamin D or calcium symptoms
MedlinePlus links very high levels to excess calcium and kidney strain; testing proves whether supplements are doing more harm than good.
Prep & Logistics
- Fasting
- Typically no fasting
- Sample
- Blood draw
- Results
- Usually 24-48 hours; many portals update the same day or the next.
- Referral
- Often self-order (check local rules)
- Markers
- Total 25-hydroxyvitamin D (D2 plus D3 combined) in ng/mL or nmol/L; some labs still split D2 and D3 on the report.
Tests That Pair With This One
Parathyroid hormone when vitamin D and calcium balance need sorting after a very low or very high storage D level.
Serum calcium when D is out of range and bone-mineral symptoms or kidney stones are in the story.
B12 when fatigue and bone-health workups overlap macrocytic blood-count patterns.
FAQ
Should everyone get a vitamin D level once a year?
Not automatically. It is most useful when low sun, malabsorption, osteoporosis risk, or symptoms fit. Routine annual testing without a reason is a conversation with your clinician, not a universal rule.
My level is 22 ng/mL. Do I need 10,000 IU?
Maybe not. MedlinePlus lists overlapping expert bands, so 22 can be fine for one clinician and low for another. Blind megadoses can overshoot; repeat testing proves the plan worked.
Why does my report show D2 and D3?
MedlinePlus explains D3 usually reflects what you made from sun or took as cholecalciferol, while D2 reflects fortified foods or ergocalciferol pills. The total 25-hydroxy number is what most doctors weigh.
Can I test right after a beach week?
Sun helps, but a single vacation does not always move storage D instantly. Follow your doctor's timing so you are not chasing noise.
Sources
Prices pulled directly from provider websites and verified by hand. Reference ranges sourced from MedlinePlus. Not generated by AI.
- GoodLabs - product page (pricing context)(verified 2026-03-23)
- Quest - consumer lab shop (pricing context)(verified 2026-03-23)
- LabCorp OnDemand - vitamin D test (pricing context)(verified 2026-03-23)
- MedlinePlus - vitamin D test overview
- MedlinePlus Medical Encyclopedia - 25-hydroxy vitamin D test (ranges, D2/D3, abnormal results)
- Clinical context: LabRecon editorial team. Not medical advice. For informational use only.
Measures serum 25-hydroxyvitamin D, the primary circulating form and standard clinical marker for vitamin D sufficiency.
Ordering note
Some labs report D2 and D3 separately. Confirm total vs. fractionated reporting when scraping.